The present invention is related to and claims priority from Japanese patent application No. Hei. 11-108455, filed Apr. 15, 1999; the contents of which are incorporated herein by reference.
The present invention relates to a device for driving and controlling a plurality of auxiliary devices with a single motor, and particularly to a motor drive-control device for driving and controlling a compressor and a warm water pump in a vehicle air-conditioning system.
Generally, in vehicle air-conditioning systems, refrigerant is circulated around a refrigerating cycle by a compressor, driven by power transmitted by a belt from a vehicle engine. Likewise, a warm water pump circulates warm water through a heater core and through a radiator. The heater core is for space-heating and the radiator is for removing heat from cooling water. The warm water pump is belt-driven by the vehicle engine. While this system works well, it has drawbacks when applied to certain types of vehicles.
Recently, vehicles such as hybrid cars have been developed. In this type of vehicle, when the vehicle comes to a stop, the engine also stops. As such, with a conventional drive mechanism, the compressor and warm water pump also stop running. Therefore, it is not possible to perform their associated space-cooling and space-heating functions.
To overcome this drawback, it is conceivable for the compressor and other elements to be driven with an electric motor during vehicle stops. Such driving is accomplished by using electrical energy stored in a battery. This energy is stored in the battery by a generator driven by the engine when the vehicle is moving. However, with respect to an air-conditioning system, the delivery capacities of the compressor and the warm water pump are preferably controlled responsive to the air-conditioning heat load. This enhances space-cooling and space-heating capacity and saves energy.
Japanese Unexamined Patent Publication No. H.9-215101 proposes a power transmitting clutch, positioned between driving wheels and a motor, which disengages the two. Such a device, for an electric car, disengages the wheels from the motor when the vehicle comes to a stop. With respect to demands of auxiliary devices, the motor is driven and controlled at an efficient speed. Therefore, auxiliary devices, such as generators (alternators), power steering pumps, negative pressure pumps, and an air-conditioning compressors are driven during vehicle stops.
However, in this technology, the motor speed is controlled to improve the motor efficiency. As such, the necessary capacity of the auxiliary devices cannot be changed with respect to changing auxiliary usage conditions. The present invention was developed in light of these drawbacks.
It is therefore an object of the present invention to drive and control a plurality of auxiliary devices with a single motor while obtaining the necessary capacity of the auxiliary corresponding to usage conditions.
To achieve this and other objects, a motor drive-control device is provided which chooses a higher of two parameters as a motor speed. The necessary speeds for a plurality of auxiliary devices is calculated. The highest of the necessary speeds is set as the auxiliary drive motor speed, and the drive motor is driven at this speed.
Therefore, in driving a plurality of auxiliary devices with a single motor, even if the usage conditions of the plurality of auxiliary devices change, the auxiliary devices can be motor-driven at the highest of the necessary speeds. By this means, it is possible to obtain the necessary capacity of the auxiliary side at all times, irrespective of changes in the usage conditions. In another aspect of the present invention, instead of motor, the plurality of auxiliary devices can be driven by engine.
In an air-conditioning system according to a second aspect of the invention, one of the auxiliary devices relates to cooling capacity and another auxiliary device relates to heating capacity. The necessary speeds of the cooling and heating devices are calculated based on the necessary cooling capacity and the necessary heating capacity.
These speeds are calculated independently, and the higher of the two speeds is set as the motor speed. Consequently, even if the air-conditioning heat load fluctuates greatly due to a large change in the usage environment, it is possible for cooling and heating capacities required by air-conditioning temperature control to be obtained at all times.
In an air-conditioning system set forth in a third aspect of the present invention, the auxiliary device relating to a cooling capacity is a compressor, and the device relating to heating capacity is a warm water water pump. The compressor is for a refrigeration cycle and the warm water pump is for circulating warm water. An evaporator, through which refrigerant of the refrigerating cycle circulates, and a heater core, through which warm water circulates, are disposed in an air-conditioning case. Air-conditioning case forms a passage through which air-conditioning air flows. Both auxiliary devices have completely different characteristics, requiring two different operating speeds. However, both are driven by a single motor. Therefore, necessary cooling and heating capacities can be obtained at all times by operating the motor at the higher required speed.
In a fourth aspect of the present invention, a temperature adjusting means for adjusting the amount of heat delivered by the heater core, is provided. As such, it is possible to freely adjust the outlet temperature of the air blown into a passenger compartment by adjustment of the heater core.
In a fifth aspect of the present invention, the compressor and the warm water pump are also driven by a vehicle engine, besides the motor. Therefore, when the compressor and the warm water pump are driven by the vehicle engine, the motor is driven by the vehicle engine and acts as a generator. That is, during driving by the vehicle engine, the motor for driving auxiliary devices can become a generator and charge a vehicle-mounted battery.
In a sixth aspect of the present invention, a first necessary warm water pump speed (Nmw1) is calculated based on a necessary heating capacity, and a second necessary warm water pump speed (Nmw2) is calculated which rises corresponding to the warm water temperature of the vehicle engine. The higher the two speeds is set as a necessary warm water pump speed (Nmw).
Thus, when the warm water temperature of the vehicle engine rises, the second necessary warm water pump speed (Nmw2) is set as the necessary warm water pump speed (Nmw). The warm water pump speed is increased to increase the flow of warm water to the cooling water radiator, thereby preventing overheating of the vehicle engine.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.